Applicant's U.S. Pat. No. 3,767,171, dated Oct. 23, 1973, discloses a small volume transit mix system wherein a transit mix unit is removably mounted on the bed of a pick up truck. If the truck is to be used for other purposes, the transit mix unit thereon must be removed by a derrick or hoist. Frequently, the party renting the truck with the concrete mixer unit thereon does not have a derrick available. Also, there are seasons of the year, particularly in the wintertime, when concrete pouring is not practical; and if the concrete mixer unit remains on the truck this ties up the truck rendering it non-useful for hauling purposes.